The present invention relates in general to the art of electrical connections and, more in particular, to a contact assembly for effecting electrical connection with standard electrical leads without the necessity of solder.
Contacts are used to make an electrical connection between desired circuit elements. The type of contacts of interest here is for a permanent connection and is used as a convenience in making an electrical circuit. In this application, an insulated lead having a conductor element is used with the contact.
Solderless contacts are well known and are used extensively. A well-known type of this contact has a pair of legs which define a slot between them. A mouth with converging sides opens into this slot and receives a lead. As the lead is forced down the slot the legs spread apart, the insulation of the lead engaged by the edges of the slot is stripped, and the edges come into electrical contact with the conductor element of the lead for an electrical connection. A mechanical lock between the conductor element and the contact arises from elastic deformation of the legs during lead insertion producing a compressive force between the legs and the conductor element. In at least one known contact, the legs actually coin the conductor element to groove it and effect mechanical interference between the lead and the contact in the direction of the length of the contact.
This type of contact is also used extensively in multiple connections. In multiple connections, several leads are wired to contacts at one time. It is extremely convenient if there is some means for firmly retaining a lead with a contact before final installation, so that wiring changes can be made when an error in an array is most likely to be noted and before final lead trimming and insulation removal.
With this type of contact, a standard installation tool has come into widespread use. The tool is used to force a lead into electrical connection with a contact and to cut off the end of the lead. This installation tool has a throat for receiving the contact. The throat has two parallel walls which, in use, parallel the plane of the contact. One of these walls is longer than the other and has a cutting edge parallel with the wall at its bottom. The cutting edge is about in the middle of its wall so as to space an actual cut from the most proximate contact surface. The shortness of the opposite parallel wall of the tool avoids excessive compression by it on a lead during the cutting process.
A most effective way of making contacts of this sort is by a punching process where the various edges and geometries are physically sheared from a metal strip by a punch press. There are known limits to this process, however. When an object to be punched becomes too thick relative to the width of slots and the like to be defined, punching is not possible.
A contact should be relatively strong so that it can take the abuse of the installation process and inadvertent forces it might receive. The strength requirements are at odds with the punch fabrication requirements for slotting to receive lead sizes commonly used, for to effect the punching operation, and yet have slot widths properly dimensioned to effect the stripping of insulation from the conductor element, the contact cannot be thick enough to be as strong as would be desired.
One use of the contact is in a jack for making a plurality of electrical connections with a plug. Typically, the plug has rigid, electrically conductive blades for connection to the contacts. Often it is required that the connection be extremely good to avoid, for example, electrical noise. This is complicated in a plug and a jack because the two are often disconnected and reconnected which can affect the quality of the connection. To get a good connection it is necessary to have the jack contacts which engage the plug blades elastically flexible to produce compressive engagement between them.